1. Field of the Invention
The present invention relates to a light source device, a projection apparatus, and a projection method using a plurality of semiconductor light source elements.
2. Description of the Related Art
In order to efficiently and safely drive a light source constituted of a plurality of semiconductor elements, it is desirable that a method in which drive power is separately optimized for each of the elements to correct unevenness in quality between the elements be employed.
For example, when a laser diode (hereinafter referred to as an “LD”) is employed as a semiconductor light-emitting element; a rate of change of light output power for a change in drive current is very large in the LD. For this reason, in a light source device in which a plurality of LDs are used, taking the variation in the light-emitting characteristic of each LD into consideration, when all the LDs are driven by a current of the same amount, differences in output power between the LDs are liable to conspicuously appear, and there are even cases where there appear some elements lead to breakage due to being given a drive current of a large amount.
Further, in a backlight in which a large number of light-emitting diodes (LEDs) which are semiconductor light-emitting elements and are used for a liquid crystal display panel, it is necessary to carry out current value control separately for each element in order to prevent unevenness in luminance due to variation of each element.
Furthermore, in a LED backlight apparatus employing the field-sequential system, in a field of each of colors of red, green, and blue, a group of LEDs each of which emits light of a corresponding color of the fields is driven by time division.
At that time, when the luminance is changed for each block in accordance with an image by providing drive current values with differences in level between the fields of the colors of red, green, and blue, or by dividing the light-emission range into a plurality of blocks, the LED group is switched in control states of several levels at high speed.
In order to realize the above-mentioned control, for each of all the constituent semiconductor light-emitting elements, a control section corresponding to each of the constituent semiconductor light-emitting elements on a one-to-one basis is separately prepared. Furthermore, a configuration is required in which a conversion table for control is used for each control section, and management or operation of data stored in the table is executed at high speed in real time.
In order to realize a configuration for carrying out control for each of a plurality of light source elements, both the hardware configuration and software processing are required to have complicated and large-scale configurations. Accordingly, this leads to an increase in the mounting area resulting from an increase in the number of components, increase in apparatus size, increase in the load of the control section, and increase in cost.